The case is being treated as a homicde and the Garland sheriff's office said two suspects were in custody and charges were expected later in the day.
The body was found on U.S. Forest Service property and the FBI is assisting.
The cause of death has not been determined.
Searchers have been looking for Roberson and his missking pickup since Thursday in country near Jessieville. Thursday night, personal items that had been in his truck were found on the roadside and authorities feared foul play.
UPDATE: from the sheriff's office:
The Garland County Sheriff’s Department announced two arrests have been made in the disappearance of 71-year old DAN ROBERSON of Jessieville. Earlier this evening, investigators formally charged 18-year old ETHAN SALLEE and a local juvenile male (aged 17) with one count each of Capital Murder for the death of ROBERSON, whose body was located earlier today in a wooded area in extreme northern Garland County.
The investigation has revealed that ROBERSON was a targeted-victim and authorities do not believe that this was a random act. Additional charges and arrests are likely.